Impeller For A Pump

ABSTRACT

An impeller for a pump, in particular for a cooling water pump of an internal combustion engine, having an impeller body having a hub, a suction-side cover disk having a central opening for suctioning a delivery medium, and having at least one blade, which is connected in one piece to the suction-side cover disk, and which has an inner section in the area of the central opening and an outer section in the area of the suction-side cover disk, the blade being implemented as three-dimensionally curved in the inner section and essentially two-dimensionally in the outer section, the impeller having a pressure-side cover disk, which is implemented as a separate part and is fixedly rotationally connected to the impeller body. The pressure-side cover disk has at least one grooved depression, shaped corresponding to the front face and the profile of the blade, for the blade for the formfitting connection thereto, on the side facing toward the blade, the impeller being produced in a casting method and each blade being free of overlaps and undercuts.

The invention relates to an impeller for a pump, in particular for a cooling water pump of an internal combustion engine, having an impeller body having a hub, a suction-side cover disk having a central opening for suctioning a delivery medium, and having at least one blade, which is integrally connected to the suction-side cover disk and which has an inner section in the area of the central opening and an outer section in the area of the suction-side cover disk, the blade being three-dimensionally curved in the inner section and being implemented essentially two-dimensionally in the outer section.

The impellers of radial pumps, as are used, for example, as cooling water pumps of motor vehicles, are predominantly implemented as so-called closed two-dimensional impellers. This means that blades are enclosed between two cover disks, whereby closed flow channels are formed within the impeller. Such closed impellers allow the achievement of good pump efficiencies. However, it is disadvantageous that the production of such impellers is complex. Such a production can be performed in two parts, for example, in that a cover disk having blades molded thereon, on the one hand, and the other cover disk, on the other hand, are produced separately from one another and connected to form the final impeller. Such a solution is disclosed, for example, in U.S. Pat. No. 2,710,580 A. However, it is also possible to produce such an impeller integrally in a casting method, a complex multipart casting mold being required in this case, however, which is equipped with a plurality of slides, which shape the flow channels. However, the blades, which are only curved two-dimensionally, only allow a limited efficiency.

In order to be able to implement the production of such an impeller simply and cost-effectively, it is desirable to design an impeller which can be produced using a simple two-part casting mold. DE 40 40 200 A discloses such a solution, in which the impeller has a pressure-side cover disk and a suction-side cover disk, between which the blades are situated, the suction-side cover disk having a central opening. The blades are situated between the cover disks, the suction-side cover disk having a central opening whose internal diameter is greater than the external diameter of the pressure-side cover disk. If the blades are implemented without undercuts, such an impeller may be produced in a two-part mold, because the demolding is readily possible. However, such an impeller has the disadvantage that the efficiency is relatively modest because of the required geometrical conditions and is substantially less than in the case of closed two-dimensional impellers.

Furthermore, being able to improve the pump efficiency of radial pumps or axial pumps through the use of three-dimensionally curved blades is known. Such a solution is described, for example, in DE 100 50 108 A. However, the production of such impellers is extraordinarily difficult and is unsuitable for use in mass production for reasons of cost and processing technology. DE 197 42 023 A discloses an impeller assembled from multiple segments, in the case of which the individual parts are easily producible, but which is complex overall and is correspondingly costly. A further impeller having three-dimensionally curved blades as a whole is described in JP 59-165895 A. The production is also correspondingly costly here.

DE 197 42 023 A discloses an impeller for a pump having spatially curved blades, which is assembled from multiple radial segments for simplified production. In addition thereto, a cover disk is put on, so that a closed impeller results. The above statements apply accordingly.

An impeller for a pump is described in EP 1 552 161 B1, which has a suction-side cover disk having a central opening for suctioning a delivery medium and at least one blade which is integrally connected to the suction-side cover disk. The blades are three-dimensionally curved in the inner section in the area of a central opening of the suction-side cover disk and are two-dimensionally curved in the outer section in the area of the suction-side cover disk. The impeller can thus be produced easily and a higher efficiency can be achieved for an open impeller. Because the impeller is implemented as open on the pressure side, decisive losses can occur due to eddying, in particular if an annular dead space is formed in the pump housing between impeller shaft and the housing on the pressure side.

An impeller for flow machines which is assembled from multiple individual parts is known from DE 38 39 190 C1, whose blades are fixed directly in the frontal area of an impeller hub with the aid of a ring element or ring element parts attached to the individual blades. The impeller has a suction-side cover disk and a pressure-side cover disk.

WO 89/02538 A1 describes a circulating pump impeller which is assembled from multiple sheet-metal parts. To achieve a rigid construction, the energy-transmitting blades are exclusively fastened to a force-transmitting cover disk. The entry area of the impeller forms a suction opening, which is implemented as an individual part, overlaps the beginnings of the blades, and is fastened thereon. A bladeless cover disk which covers the blade channels is fastened between the impeller exit and the maximum diameter of the suction opening at the blades.

A multipart circulating pump impeller is known from EP 0 284 246 A1, which has impeller blades having a pressure-side cover disk and a suction-side cover disk, the suction-side cover disk being implemented as an individual part and being connected to the impeller.

The object of the invention is to avoid these disadvantages and, with simple production capability of the impeller, to achieve an improvement of the efficiency in comparison to known impeller embodiments.

This is achieved according to the invention in that the impeller has a pressure-side cover disk, which is implemented as a separate part and is fixedly rotationally connected to the impeller body, and the pressure-side cover disk has at least one grooved depression, which is shaped corresponding to the front face and the profile of the blade, for the blade for positive connection thereto on the side facing toward the blade. The impeller can thus be produced having two-dimensional and three-dimensional efficiency-optimal shaped impeller blades in a simple manner, flow losses as a result of eddies being prevented by the pressure-side cover of the impeller. The impeller according to the invention thus unifies the advantages of semi-open impellers having three-dimensionally curved blades with closed impellers. Through the semi-open construction of the impeller, three-dimensionally curved impeller blade structures may also be readily produced in mass production. The impeller is then connected rotationally fixed to the pressure-side cover disk, so that closed, spatially curved flow channels arise in the impeller.

A rotationally-secure connection between the two parts of the impeller is made possible using simple means by the depressions.

In the case of pumps in which an annular dead space is formed between impeller shaft and pump housing on the pressure side of the impeller, it is advantageous if the diameter of the pressure-side cover disk at least corresponds to the diameter of an adjoining ring space, which is formed between impeller shaft and housing. If the ring space is laterally delimited by a shaft seal, it can be provided that the diameter of the pressure-side cover disk essentially corresponds to the diameter of a shaft seal which delimits the ring space.

An embodiment of the invention having particularly simple production provides that the pressure-side cover disk is implemented as planar.

In contrast, a particularly high efficiency may be achieved if the pressure-side cover disk is implemented as concavely curved on the side facing toward the blades. In order to keep weight and production costs of the impeller as low as possible, the wall thickness of the pressure-side cover disk approximately corresponds to the wall thickness of the suction-side cover disk.

Outlet-side pressure losses may be kept as small as possible if the diameter of the pressure-side cover disk essentially corresponds to the diameter of the suction-side cover disk. It is particularly advantageous if the flow surface of the pressure-side cover disk is implemented running with the lateral surface of the outlet-side pressure spiral.

If the blades are free of overlaps and undercuts in the inner section, i.e., if the rear edge of one blade is in front of the front edge of the closest blade in axial view, the impeller can be produced in a two-part mold and can be demolded by simple translational movement of the two mold halves.

In this manner, the impeller can be produced in a simple manner, for example, in a die-casting method or also in a plastic injection-molding method. However, it is also possible to use steel casting or iron casting methods. In certain circumstances, sheet-metal shaping technologies may also be used.

It is particularly favorable for increasing the efficiency if an axial projection is provided on the cover disk in the area of the opening, which protrudes in the direction of the suction side. In this manner, it is possible to implement the intake area, which is particularly critical for flow technology, optimally.

The invention is explained in greater detail hereafter on the basis of figures. In the figures:

FIG. 1 shows a pump having an impeller according to the invention in a longitudinal section in a first embodiment variant;

FIG. 2 shows a pump having an impeller according to the invention in a longitudinal section in a second embodiment variant;

FIG. 3 shows the impeller from FIG. 2 in a suction-side diagonal view;

FIG. 4 shows the impeller in a pressure-side diagonal view;

FIG. 5 shows a pump having an impeller according to the invention in a longitudinal section in a third embodiment variant;

FIG. 6 shows the impeller in a suction-side diagonal view;

FIG. 7 shows the impeller in a pressure-side diagonal view;

FIG. 8 shows a pump having an impeller according to the invention in a longitudinal section in a fourth embodiment variant;

FIG. 9 shows the impeller from FIG. 8 in a suction-side diagonal view;

FIG. 10 shows a pump having an impeller according to the invention in a longitudinal section in a fifth embodiment variant;

FIG. 11 shows the impeller from FIG. 10 in a pressure-side diagonal view; and

FIG. 12 shows the impeller in an exploded view.

The radial pumps shown in the figures each comprise a housing 1 (only partially shown), having a bearing part 2 and a housing outer wall 23. A pump shaft 4, on one end of which an impeller 5 is fastened, is mounted using a bearing 3 (only schematically shown). A pump cover 7, which encloses the suction chamber 8 of the pump, is fastened on the housing 23. The pressure chamber 9 of the pump is situated in the radial direction outside the impeller 5. A shaft seal 10, which is implemented as an axial face seal, for example, seals suction chamber 8 and pressure chamber 9 in relation to the bearing part 2.

The impeller 5 has an impeller body 5 a having a hub 11, which is connected rotationally fixed to the impeller shaft 4. Blades 13, which are implemented to deliver the delivery medium, originate from the outer circumference of the hub 11. The blades 13 are connected in one piece to a suction-side cover disk 14, which has a central opening 15, through which the delivery medium is suctioned. The impeller body 5 a, which is implemented as semi-open per se, is connected rotationally fixed to a pressure-side cover disk 24 on the diametrically opposing side. The pressure-side cover disk 24 can be connected to the impeller body 5 a using a press fit. The wall thickness s₁ of the pressure-side cover disk 24 approximately corresponds to the wall thickness s₂ of the suction-side cover disk 14. The size and the shape of the pressure-side cover disk 24 vary in the embodiment variants shown in FIG. 1 through FIG. 11.

The blades 13 have an inner section 13 a in the area of the opening 15 and an outer section 13 b in the area of the suction-side cover disk 14. The diameter d of the opening 15 corresponds to approximately half of the diameter D of the impeller 5 in the exemplary embodiment.

The inner section 13 a of the blades 13 is curved in a spiral, but is free of overlaps or undercuts in the axial direction, in order to ensure a simple demolding capability. In outer section 13 b, the blades 13, except for possible casting bevels, have a rectangular cross-section, which is perpendicular to the suction-side cover disk 14, in order to also ensure a simple demolding capability here.

A convex surface 16 of the blades 13 extends smoothly from the inner section 13 a to the outer section 13 b. A concave surface 17 is implemented diametrically opposite to the convex surface 16. An edge 18, which is required by casting technology, is implemented in the concave surface 17 from the inner section 13 a to the outer section 13 b. The suction-side cover disk 14 is rounded in the transition to the opening 15 at 20, in order to achieve optimum flow deflection. An axial projection 21 in the area of the opening 15 allows a possible flow optimization. In the outer section 13 b, the blades 13 have a front face 22 on the pressure side which—at least partially—forms the support for the pressure-side cover disk 24. The front face 22 can be in a plane perpendicular to the axis 5′ of the impeller 5 (FIG. 1, and FIG. 5 through FIG. 7) or can be curved convexly toward the pressure-side cover disk 24.

FIG. 1 shows an embodiment in which the diameter d₁ of the pressure-side cover disk 24 essentially corresponds to the diameter of the shaft seal 10, which is situated in a ring space 25 spanned by the impeller shaft 4 and the housing 2. Eddies in the ring space 25 due to the impeller 5 are prevented by the pressure-side cover disk 24.

FIG. 2 shows an embodiment in which the pressure-side cover disk 24 is implemented as slightly raised and slightly concave on the side 24 a facing toward the blades 13 to form flow channels. This allows the flow losses to be reduced.

FIG. 5 through FIG. 11 show embodiments in which the diameter d₁ of the pressure-side cover disk 24 is approximately equal to the diameter d₂ of the suction-side cover disk 14. The pressure-side cover disk 24 has a significantly greater diameter than the ring space 25. Flow losses as a result of eddies and separation on the pressure side of the impeller 5 may thus be further reduced.

While the pressure-side cover disk 24 is implemented as planar in FIG. 5, in FIG. 8 and FIG. 10, the pressure-side cover disk 24 is also shaped concavely corresponding to the flow channels of the impeller 5 on the side facing toward the impeller, in order to avoid flow separation within the impeller 5.

As is obvious from FIG. 10 and FIG. 12, the pressure-side cover disk 24 has depressions 26 shaped corresponding to the front faces 22 of the blades 13 on the side 24 a facing toward the blades 13. When the impeller 5 and the pressure-side cover disk 24 are assembled, the front sides 22 of the blades 13 come to rest in the depressions 26 of the pressure-side cover disk 24, whereby a positive rotational connection of the impeller 5 and the pressure-side cover disk 24 is produced, the impeller 5 and the pressure-side cover disk 24 being able to be connected to one another by a press fit connection. It is also possible to fix the impeller body 5 a and the pressure-side cover disk 24 through a friction-locked and positive connection and to fix both parts via a screw connection (not shown in greater detail) on the impeller shaft 4.

Using the impeller 5 described according to the invention, pumps having extremely high efficiency may be produced cost-effectively, which exceed the efficiency of pumps having closed impellers having two-dimensional blades. The impeller 5 is very easy to produce in casting technology because of its simple demolding capability. In addition, such an impeller 5 has outstanding cavitation properties.

Because of the pressure-side cover disk, the impeller 5 according to the invention is preferably suitable for retrofitting and equipping pumps having a relatively large ring space 25, without the pump housing 2 having to be replaced or altered. 

1. An impeller for a pump, in particular for a cooling water pump of an internal combustion engine, having an impeller body having a hub, a suction-side cover disk having a central opening for suctioning a delivery medium, and having at least one blade, which is integrally connected to the suction-side cover disk, and which has an inner section in the area of the central opening and an outer section in the area of the suction-side cover disk, the blade being implemented as three-dimensionally curved in the inner section and essentially two-dimensionally in the outer section, the impeller has a pressure-side cover disk, which is implemented as a separate part and is fixedly rotationally connected to the impeller body, wherein the pressure-side cover disk has at least one grooved depression, which is shaped corresponding to the front face and the profile of the blade, for the blade for the positive connection thereto on the side facing toward the blade, the impeller being produced in a casting method and each blade being free of overlaps and undercuts.
 2. The impeller according to claim 1, wherein a diameter of the pressure-side cover disk at least corresponds to a diameter of an adjoining ring space, which is formed between the impeller shaft and housing.
 3. The impeller according to claim 2, wherein the diameter of the pressure-side cover disk essentially corresponds to a diameter of a shaft seal, which delimits the ring space.
 4. The impeller according to claim 2, wherein the diameter (d1) of the pressure-side cover disk essentially corresponds to a diameter (d2) of the suction-side cover disk.
 5. The impeller according to claim 1, wherein the pressure-side cover disk is planar.
 6. The impeller according to claim 1, wherein the pressure-side cover disk is concavely curved on a side facing toward the blade.
 7. The impeller according to claim 1, wherein each blade is two-dimensionally curved and is perpendicular to the plane of the suction-side cover disk in the area of the suction-side cover disk.
 8. (canceled)
 9. The impeller according to claim 1, wherein a wall thickness (s₁) of the pressure-side cover disk essentially corresponds to a wall thickness (s₂) of the suction-side cover disk. 